FMF Q4 installed on 2010
 

I've just got my 2010 250s back from my area's local bike guru, with an FMF Q4 installed.

Wow, what a difference... definitely quicker and torquier, almost like a whole new bike. *definitely* louder. It backfires a smidge when coming off the throttle at times (not a loud detonation, but more like a low pop). Bike guru says that jetting might not be neccesary - told me to ride it and report back it I want it jetted.

Anybody running just the pipe? Should I have it jetted? Since he'll definitely make more money off of me with it jetted (and, more importantly, because he's the expert and I'm not), I'm even more inclined to believe him when he says it might not even be neccesary;)

Proper jetting with out the pipe will make the bike run better, so even more with the pipe. Read around here and see about getting a KLX snorkel.

David

Wow, have you not melted that blinker yet?

It's not a question of whether you can survive without jetting, but whether there is more power and better running with the proper jetting. I would rejet after you have made a decision on air filter and snorkel upgrades.

If yours is a Cal. model it's jetted super lean, probably worth enrichening unless you live at 18,000 feet in which case the stock jetting should run just fine. :)

No need to quit now get a performance air filter and just pull your snorkle out of the top of the airbox and throw it away. Then there will be no question if there is a need to jet that thing.

hi y'all:

new member in pa. i just got a 2010 klx250s yesterday. i researched the various models and makes and chose the kawasaki. many articles mentioned "jetting" the bike to get better performance. and something about "muzzy" exhust. can you all help me with some proper terms and descriptions so that before i pick it up, i can tell the shop what i want done to improve the performance?

thankx in advance,

greg

Muzzy is one of several manufacturers of aftermarket mufflers and header pipes. These are all (more or less) noisier than stock, but allow for more air flow and thus more power. Jetting refers to the little jets in the carburetor that allow fuel to mix with air to feed the engine. These bikes are "lean" from the factory, meaning they arguably don't give the bike enough fuel. Putting on a muzzy allows more air flow, and thus it will be even more lean than stock unless you "jet" with larger jet. Lots of us here enjoy the "DynoJet" brand of jets and needle in the carb, but there are others. You may also want to do something with the airbox to allow more air into the carb (e.g. remove the lid, or snorkel, or replace snorkel with larger). Use the search function and read up on some of the sticky FAQs to learn more.

oh, and colinclive, welcome to the forum! You'll find lots of good stuff and help around here. Enjoy your new bike.

Oldfart,

When you can give some more input about the Q4 w/o jetting please do. I want to buy it and bolt it on but haven't due to the carb re jet issues. I can bolt stuff fine but have never messed with carbs. Have you pulled your snorkel? Or just the Q4? I have the 09 Cali model too and am at roughly 500 ft elevation. So if it os working for you maybe I will go for it...

These bikes are lean from the word go.
They need to be jetted even with the stock exhaust in MOST cases to run right.
If you are happy with the performance of the bike overall, you still need to jet it rich to get rid of the cold starting issue. You may as well just go for it and jet. If you have a pipe jet it when you put the pipe on. if you are going to open up the intake with a snorkel mod or lid removal, free flow filter, etc... jet it.
you can install a pipe and not jet because the limiting factor is still the intake all clogged up. If you mod the intake and the exhaust, you MUST rejet.
I don't see how anyone can be happy with this bike at all if it is pure stock becasue the throttle response is terrible. jet it and be done with it.